Today, it is generally known to pack e.g. Christmas trees on pallets, and it is also known to compress these Christmas trees so that the pallets can contain more trees than if the trees are in their uncompressed state. The compression takes place in that the trees on the packed pallet are subjected to a pressure vertically and/or horizontally, thereby causing compression of the trees. The trees are tied while the pressure is maintained, and then the pallet with the compressed trees is ready for further distribution.
Various devices for compressed packing of particularly Christmas trees on pallets are known, which devices operate according to different principles.
The devices may be divided into two groups, viz. devices wherein packing is carried on pallets which in themselves are not provided with lateral supports, and wherein tying of the packed material is performed, e.g. so-called Europallets, and devices wherein packing is carried out on pallets which in themselves are provided with lateral supports protruding upwards from the pallet, and wherein no tying of the packed material is performed.
When Christmas trees are packed on pallets without lateral supports, the packed and compressed trees are secured by laths which are positioned such that, together with the pallet, they form a frame at each end of the pallet, following which the two frames are separately tied with a steel or plastics band.
A device for performing such a packing of pallets without lateral supports is known from e.g. Danish Utility Model No. 96 00153, which shows a device for mounting on the lifters of a tractor and having a top part which is movable between a vertical position and a horizontal position, and which is capable of performing vertical compression of the packed tress in the horizontal position.
However, tying with steel or plastics band around frames of laths has a number of drawbacks, such as for example:
special holders are required for securing the laths with respect to the pallet immediately before the steel or plastics band is tied, PA1 special tools are required for closing the steel or plastics band to achieve the necessary tightening of the band, it is not possible to perform selective unloading, because all the trees are loosened at the same time when the steel or plastics band is cut, which also requires special tools, PA1 danger of personal injury when the steel or plastics bands are cut, as these exhibit a whipping effect when they are loosened, PA1 the tied steel or plastics band gives an increased amount of waste, and is moreover difficult to handle when it is to be disposed of. PA1 the pallet is already provided with the necessary supports which are merely connected by strings or the like, PA1 it is possible to perform selective unloading, as the trees may be removed from the top of the loaded pallet after the uppermost strings or the like between opposite lateral supports have been removed, PA1 it is possible to unload individual trees and optionally supplement with new ones for further distribution, PA1 if the lateral supports are removable, all the trees may be removed from the pallet at the same time, if desired, by removing all the lateral supports, PA1 if the lateral supports are removable, the trees may be unloaded from one side merely by removing the lateral supports on one side of the pallet, PA1 there is less danger of personal injury, as there are no steel or plastics bands which have to be cut, PA1 if the pallet is arranged as stated in Danish Patent No. 172 068, both pallet and lateral supports as well as strings or the like may be returned, which means that there will be no waste.
Because of these drawbacks and for other reasons, other pallets have been developed for the packing of e.g. Christmas trees, said pallets being provided with lateral supports.
Danish Patent No. 169 147 discloses a pallet system which consists of a relatively fragile pallet, a so-called export pallet, which is provided with lateral supports. When being packed with trees, the export pallet is supported by a more rigid and stronger pallet, a so-called forest pallet. After packing, the trees are compressed on the pallet in that a fork assembly mounted on a tractor is pressed down on the trees, and then the opposite lateral supports of the export pallet are connected by chains. The export pallet with the packed trees may then be removed from the forest pallet and e.g. be loaded on a truck for further distribution.
The said export pallet has a size of 2.times.2.4 m.sup.2, which means that the packed pallets are so heavy that relatively strong equipment has to be used for loading and unloading. The size also means that a packed pallet of this type may be stable without the use of lateral supports.
To overcome the handling problems of the relatively large export pallet smaller and lighter pallets have been developed, e.g., as shown in Danish Patent No. 172 068, which discloses a pallet having lateral supports which is likewise of a relatively fragile structure, and in which the opposite lateral supports are also connected during the packing with trees.
The advantages of using a pallet having lateral supports include:
A general problem of the packing of trees and decorative greenery is that sliding of material takes place during loading and compression, so that it is difficult to keep the ends of the packed trees and decorative greenery within the permissible boundaries, which are defined e.g. by the internal dimensions of a truck. Sliding occurs in particular at the moment when the trees are placed on the pallet, which frequently takes place by throwing the trees on to the pallet, which subjects the underlying trees to pressure impacts. Sliding is difficult to control and therefore causes the pallet to have a very nonuniform face in the areas--typically the ends--where there is no control of the trees.
If the trees and the decorative greenery protrude beyond the permissible boundaries, the pallet cannot be loaded on a truck, and at worst the whole pallet has to be repacked. To avoid this, the pallets are frequently packed more narrowly than necessary, whereby the capacity of the truck is not utilized optimally.
In addition to packing Christmas trees on pallets, it is also known to pack Christmas trees in a sack, cf. Danish Patent Application No. 0439/95. The sack is kept distended during filling by means of a stationary frame which holds the sides of the sack. When the sack is full, the trees are compressed in that annular straps pull the sides of the sack toward each other, following which these are coupled together by means of double hooks.
This form of packing Christmas trees, however, have some of the same drawbacks as are mentioned above. For example, a sack indeed reduces sliding during loading, but since the sack consists of a flexible material, sliding will still take place. Sliding and the flexible material of the sack also mean that a packed sack will always bulge in all directions, and as a consequence of this the sacks cannot be stacked optimally, either at the side of each other or on top of each other. In addition, a packed sack must be handled by means of a crane, both during handling in the forest and during loading on and unloading from a truck.